Method, apparatus and system of determining a time of arrival of a wireless communication signal

ABSTRACT

Some demonstrative embodiments include devices, systems and methods of determining a Time of Arrival (ToA) of a wireless communication signal. For example, a method may include receiving a signal over a wireless communication channel, detecting a symbol boundary of a symbol of the signal, and determining a ToA of the signal based on the symbol boundary and a channel estimation of the wireless communication channel.

CROSS REFERENCE

This application is a National Phase Application of PCT InternationalApplication No. PCT/US2012/034263, International Filing Date Apr. 19,2012, which in turn claims the benefit of and priority from U.S.Provisional Patent application No. 61/556,891, entitled “Method,Apparatus and System For Measuring of Time of Arrival of Packets”, filedNov. 8, 2011, the entire disclosures of which are incorporated herein byreference.

BACKGROUND

In general, many of the positioning systems rely on timing measurementsthat may be used to calculate ranges. An example for such a system is aglobal positioning system (GPS).

IEEE 802.11v standard for Information Technology—Telecommunications andinformation exchange between systems—Local and metropolitan areanetworks—Specific requirements Part 11: Wireless LAN Medium AccessControl (MAC) and Physical Layer (PHY) specifications Amendment 8: IEEE802.11 Wireless Network Management (“the IEEE 802.11v standard”),defines a timing measurement that may be used for positioning of adevice.

However, the accuracy of this measurement according to the IEEE 802.11vstandard is not sufficient for indoor positioning and navigation, e.g.,because a range measurement error is above 1 meter. For example, theIEEE 802.11v standard defines a maximum resolution of 10 nanoseconds,which is not sufficient for indoor positioning and/or indoor navigation.

BRIEF DESCRIPTION OF THE DRAWINGS

For simplicity and clarity of illustration, elements shown in thefigures have not necessarily been drawn to scale. For example, thedimensions of some of the elements may be exaggerated relative to otherelements for clarity of presentation. Furthermore, reference numeralsmay be repeated among the figures to indicate corresponding or analogouselements. The figures are listed below.

FIG. 1 is a schematic block diagram illustration of a system inaccordance with some demonstrative embodiments.

FIG. 2 is a schematic illustration of time components utilized fordetermining a Time of Arrival (ToA), in accordance with somedemonstrative embodiments.

FIG. 3 is a schematic illustration of two graphs depicting channelestimations sampled at first and second sampling rates in a frequencydomain, two graphs depicting the channel impulse response of the channelestimation sampled at the first and second sampling rates, and twographs depicting Multiple-Signal-Classification (MUSIC) spectrumscorresponding to the channel estimation sampled at the first and secondsampling rates.

FIG. 4 is a schematic illustration of a sequence diagram, whichdemonstrates operations and interactions between a first device and asecond device, in accordance with some demonstrative embodiments.

FIG. 5 is a schematic illustration of a method of determining a ToA of awireless communication signal, in accordance with some demonstrativeembodiments.

FIG. 6 is a schematic illustration of an article of manufacture, inaccordance with some demonstrative embodiments.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However it will be understood by those of ordinary skill in the art thatthe present invention may be practiced without these specific details.In other instances, well-known methods, procedures, components andcircuits have not been described in detail so as not to obscure thepresent invention.

Some portions of the detailed description, which follow, are presentedin terms of algorithms and symbolic representations of operations ondata bits or binary digital signals within a computer memory. Thesealgorithmic descriptions and representations may be the techniques usedby those skilled in the data processing arts to convey the substance oftheir work to others skilled in the art.

Unless specifically stated otherwise, as apparent from the followingdiscussions, it is appreciated that throughout the specificationdiscussions utilizing terms such as “processing”, “computing”,“calculating”, “determining”, or the like, refer to the action and/orprocesses of a computer or computing system, or similar electroniccomputing device, that manipulates and/or transforms data represented asphysical, such as electronic, quantities within the computing system'sregisters and/or memories into other data similarly represented asphysical quantities within the computing system's memories, registers orother such information storage, or transmission devices. The terms “a”or “an”, as used herein, are defined as one, or more than one. The termplurality, as used herein, is defined as two, or more than two. The termanother, as used herein, is defined as, at least a second or more. Theterms including and/or having, as used herein, are defined as, but notlimited to, comprising. The term coupled as used herein, is defined asoperably connected in any desired form for example, mechanically,electronically, digitally, directly, by software, by hardware and thelike.

The term “wireless device” as used herein includes, for example, adevice capable of wireless communication, a communication device capableof wireless communication, a communication station capable of wirelesscommunication, a portable or non-portable device capable of wirelesscommunication, or the like. In some embodiments, a wireless device maybe or may include a peripheral device that is integrated with acomputer, or a peripheral device that is attached to a computer. In someembodiments, the term “wireless device” may optionally include awireless service.

The phrase “mobile device” as used herein includes any suitableportable, movable, transportable, non-stationary and/or non-fixedwireless device. The mobile device may include, for example, a mobilecomputer, a laptop computer, a notebook computer, a tablet computer, ahandheld computer, a handheld device, a Personal Digital Assistant (PDA)device, a handheld PDA device, a hybrid device, a consumer device, awireless communication device, a cellular device, a cellular telephone,a mobile internet device (MID), a wireless telephone, a PersonalCommunication Systems (PCS) device, a PDA device which incorporates awireless communication device, a mobile or portable Global PositioningSystem (GPS) device, a device which incorporates a GPS receiver ortransceiver or chip, a device which incorporates an RFID element orchip, a wireless handheld device (e.g., BlackBerry, Palm Treo), aWireless Application Protocol (WAP) device, and the like.

It should be understood that the present invention may be used in avariety of applications. Although the present invention is not limitedin this respect, the circuits and techniques disclosed herein may beused in many apparatuses such as stations of a radio system. Stationsintended to be included within the scope of the present inventioninclude, by way of example only, WLAN stations, wireless personalnetwork (WPAN), cellular networks, smartphone devices and the like.

Some embodiments may be used in conjunction with various devices andsystems, for example, a video device, an audio device, an audio-video(A/V) device, a Set-Top-Box (STB), a Blu-ray disc (BD) player, a BDrecorder, a Digital Video Disc (DVD) player, a High Definition (HD) DVDplayer, a DVD recorder, a HD DVD recorder, a Personal Video Recorder(PVR), a broadcast HD receiver, a video source, an audio source, a videosink, an audio sink, a stereo tuner, a broadcast radio receiver, adisplay, a flat panel display, a Personal Media Player (PMP), a digitalvideo camera (DVC), a digital audio player, a speaker, an audioreceiver, an audio amplifier, a data source, a data sink, a DigitalStill camera (DSC), a Personal Computer (PC), a desktop computer, amobile computer, a laptop computer, a notebook computer, a tabletcomputer, a server computer, a handheld computer, a handheld device, aPersonal Digital Assistant (PDA) device, a handheld PDA device, anon-board device, an off-board device, a hybrid device, a vehiculardevice, a non-vehicular device, a mobile or portable device, a consumerdevice, a non-mobile or non-portable device, a wireless communicationstation, a wireless communication device, a wireless AP, a wired orwireless router, a wired or wireless modem, a wired or wireless network,a wireless area network, a Wireless Video Area Network (WVAN), a LocalArea Network (LAN), a WLAN, a PAN, a WPAN, devices and/or networksoperating in accordance with existing WirelessHDTM and/orWireless-Gigabit-Alliance (WGA) specifications and/or future versionsand/or derivatives thereof, devices and/or networks operating inaccordance with existing IEEE 802.11 (IEEE 802.11-2007: Wireless LANMedium Access Control (MAC) and Physical Layer (PHY) Specifications)standards and amendments (“the IEEE 802.11 standards”), e.g., IEEE802.11v standard for Information Technology—Telecommunications andinformation exchange between systems—Local and metropolitan areanetworks—Specific requirements Part 11: Wireless LAN Medium AccessControl (MAC) and Physical Layer (PHY) specifications Amendment 8: IEEE802.11 Wireless Network Management (“the IEEE 802.11v standard”), IEEE802.16 standards, and/or future versions and/or derivatives thereof,units and/or devices which are part of the above networks, one wayand/or two-way radio communication systems, cellular radio-telephonecommunication systems, Wireless-Display (WiDi) device, a cellulartelephone, a wireless telephone, a Personal Communication Systems (PCS)device, a PDA device which incorporates a wireless communication device,a mobile or portable Global Positioning System (GPS) device, a devicewhich incorporates a GPS receiver or transceiver or chip, a device whichincorporates an RFID element or chip, a device which incorporates anlocation base system such as for example GPS, element or chip, a devicewhich incorporates a near field communication (NFC) element or chip, adevice which operate under mobile phone operating systems (OS) such as,for example, iOS™, Android™, Windows® or the like, a Multiple InputMultiple Output (MIMO) transceiver or device, a Single Input MultipleOutput (SIMO) transceiver or device, a Multiple Input Single Output(MISO) transceiver or device, a device having one or more internalantennas and/or external antennas, Digital Video Broadcast (DVB) devicesor systems, multi-standard radio devices or systems, a wired or wirelesshandheld device (e.g., BlackBerry, Palm Treo), a Wireless ApplicationProtocol (WAP) device, or the like.

Some embodiments may be used in conjunction with one or more types ofwireless communication signals and/or systems, for example, RadioFrequency (RF), Infra Red (IR), Frequency-Division Multiplexing (FDM),Orthogonal FDM (OFDM), Time-Division Multiplexing (TDM), Time-DivisionMultiple Access (TDMA), Extended TDMA (E-TDMA), General Packet RadioService (GPRS), extended GPRS, Code-Division Multiple Access (CDMA),Wideband CDMA (WCDMA), CDMA 2000, single-carrier CDMA, multi-carrierCDMA, Multi-Carrier Modulation (MDM), Discrete Multi-Tone (DMT),Bluetooth®, Global Positioning System (GPS), Wi-Fi, Wi-Max, ZigBee™,Ultra-Wideband (UWB), Global System for Mobile communication (GSM), 2G,2.5G, 3G, 3.5G, 4G, 5G, Enhanced Data rates for GSM Evolution (EDGE), orthe like. Other embodiments may be used in various other devices,systems and/or networks.

Some demonstrative embodiments may be used in conjunction with awireless communication network communicating over a frequency band of 60GHz. However, other embodiments may be implemented utilizing any othersuitable wireless communication frequency bands, for example, anExtremely High Frequency (EHF) band (the millimeter wave (mmwave)frequency band), e.g., a frequency band within the frequency band ofbetween 30 Ghz and 300 GHZ, a WLAN frequency band, a WPAN frequencyband, and the like.

Some demonstrative embodiments include a method including receiving asignal over a wireless communication channel; detecting a symbolboundary of a symbol of the signal; and determining a time of arrival(ToA) of the signal based on the symbol boundary and a channelestimation of the wireless communication channel.

In some demonstrative embodiments, the method may include determining apath delay corresponding to the wireless communication channel based onthe channel estimation; and determining the ToA of the signal based onthe symbol boundary and the path delay.

In some demonstrative embodiments, determining the path delay mayinclude identifying a discrete phase vector (phasor) component of thechannel estimation in a frequency domain; and determining the path delayaccording to a timing of the discrete phasor component.

In some demonstrative embodiments, identifying the discrete phasorcomponent may include identifying a lowest phasor component of thechannel estimation in the frequency domain.

In some demonstrative embodiments, the path delay may include aline-of-sight (LoS) path delay corresponding to a LoS path within thewireless communication channel.

In some demonstrative embodiments, the method may include identifying alowest phasor component of the channel estimation in a frequency domain;and determining the LoS path delay according to a timing of the lowestphasor component.

In some demonstrative embodiments, determining the path delay mayinclude performing an Eigen decomposition on a covariance matrixcorresponding to the channel estimation.

In some demonstrative embodiments, determining the path delay mayinclude applying a super-resolution frequency-estimation algorithm toconvert the channel estimation from a frequency domain into a timedomain.

In some demonstrative embodiments, the super-resolutionfrequency-estimation algorithm may include aMultiple-Signal-Classification (MUSIC) algorithm.

In some demonstrative embodiments, the method may include determining atime-of-flight (ToF) between a receiver of the signal and a transmitterof the signal based on the ToA of the signal.

In some demonstrative embodiments, the method may include determining adistance between the transmitter and receiver based on the ToF.

In some demonstrative embodiments, the method may include determining alocation of a receiver of the signal based on the ToA of the signal.

In some demonstrative embodiments, detecting the symbol boundary mayinclude detecting a ToA of the symbol.

In some demonstrative embodiments, the signal may include anOrthogonal-Frequency-Division-Multiplexing (OFDM) signal, and the symbolmay include an OFDM symbol.

In some demonstrative embodiments, a wireless communication device mayinclude ToA calculator to determine a path delay corresponding to awireless communication channel, and to calculate a ToA of a signalreceived over the wireless communication channel based on the path delayand on a detected symbol boundary of a symbol of the signal.

In some demonstrative embodiments, a wireless communication system mayinclude a wireless communication device to receive a first message fromanother wireless communication device over a wireless communicationchannel, to calculate a ToA of the first message based on a path delaycorresponding to the wireless communication channel and on a detectedsymbol boundary of a symbol of the message, and to transmit to the otherwireless communication device a second message including a valuecorresponding to the ToA.

Reference is now made to FIG. 1, which schematically illustrates a blockdiagram of a system 100 in accordance with some demonstrativeembodiments.

As shown in FIG. 1, in some demonstrative embodiments, system 100 mayinclude a wireless communication network including one or more wirelesscommunication devices, e.g., wireless communication devices 102 and/or104, capable of communicating content, data, information and/or signalsover a wireless communication channel 110, for example, a radio channel,an IR channel, a RF channel, a Wireless Fidelity (WiFi) channel, and thelike. One or more elements of system 100 may optionally be capable ofcommunicating over any suitable wired communication links.

In some demonstrative embodiments, wireless communication devices 102and/or 104 include, for example, one or more wireless transmitters,receivers and/or transceivers able to send and/or receive wirelesscommunication signals, RF signals, frames, blocks, transmission streams,packets, messages, data items, and/or data.

In some demonstrative embodiments, wireless communication devices 102and/or 104 may include or may be implemented as part of a mobile orportable device. For example, wireless communication devices 102 and/or104 may include or may be implemented as part a mobile computer, alaptop computer, a notebook computer, a tablet computer, a handheldcomputer, a handheld device, a PDA device, a handheld PDA device, anon-board device, an off-board device, a hybrid device (e.g., combiningcellular phone functionalities with PDA device functionalities), aconsumer device, a vehicular device, a non-vehicular device, a cellulartelephone, a PCS device, a PDA device which incorporates a wirelesscommunication device, a mobile or portable GPS device, a relativelysmall computing device, a non-desktop computer, a “Carry Small LiveLarge” (CSLL) device, an Ultra Mobile Device (UMD), an Ultra Mobile PC(UMPC), a Mobile Internet Device (MID), an “Origami” device or computingdevice, a device that supports Dynamically Composable Computing (DCC), acontext-aware device, a video device, an audio device, an A/V device, aBD player, a BD recorder, a DVD player, a HD DVD player, a DVD recorder,a HD DVD recorder, a PVR, a broadcast HD receiver, a video sink, anaudio sink, a stereo tuner, a broadcast radio receiver, a flat paneldisplay, a PMP, a DVC, a digital audio player, a speaker, an audioreceiver, a gaming device, an audio amplifier, a data source, a datasink, a DSC, a media player, a Smartphone, a television, a music player,or the like.

In some demonstrative embodiments, system 100 may include anindoor-based system located within an indoor premises and/or location,e.g., a building, a shop, an office, a shopping center, a mall, and thelike. In other embodiments, system 100 may include an outdoor systemlocated outdoors and/or in a combination of one or more indoorlocations, e.g., one or more buildings, and/or one or more outdoorlocations. In one example, system 100 may be deployed within a shoppingcenter or a campus.

Wireless communication devices 102 and/or 104 may include, for example,one or more of a processor 148, an input unit 140, an output unit 142, amemory unit 144, and a storage unit 146. Wireless communication devices102 and/or 104 may optionally include other suitable hardware componentsand/or software components. In some demonstrative embodiments, some orall of the components of one or more of wireless communication devices102 and/or 104 may be enclosed in a common housing or packaging, and maybe interconnected or operably associated using one or more wired orwireless links. In other embodiments, components of one or more ofwireless communication devices 102 and/or 104 may be distributed amongmultiple or separate devices.

Processor 148 includes, for example, a Central Processing Unit (CPU), aDigital Signal Processor (DSP), one or more processor cores, asingle-core processor, a dual-core processor, a multiple-core processor,a microprocessor, a host processor, a controller, a plurality ofprocessors or controllers, a chip, a microchip, one or more circuits,circuitry, a logic unit, an Integrated Circuit (IC), anApplication-Specific IC (ASIC), or any other suitable multi-purpose orspecific processor or controller. Processor 148 executes instructions,for example, of an Operating System (OS) of wireless communicationdevices 102 and/or 104 and/or of one or more suitable applications.

Input unit 140 includes, for example, a keyboard, a keypad, a mouse, atouch-pad, a track-ball, a stylus, a microphone, or other suitablepointing device or input device. Output unit 142 includes, for example,a monitor, a screen, a flat panel display, a Cathode Ray Tube (CRT)display unit, a Liquid Crystal Display (LCD) display unit, a plasmadisplay unit, one or more audio speakers or earphones, or other suitableoutput devices.

Memory unit 144 includes, for example, a Random Access Memory (RAM), aRead Only Memory (ROM), a Dynamic RAM (DRAM), a Synchronous DRAM(SD-RAM), a flash memory, a volatile memory, a non-volatile memory, acache memory, a buffer, a short term memory unit, a long term memoryunit, or other suitable memory units. Storage unit 146 includes, forexample, a hard disk drive, a floppy disk drive, a Compact Disk (CD)drive, a CD-ROM drive, a DVD drive, or other suitable removable ornon-removable storage units. Memory unit 144 and/or storage unit 146,for example, may store data processed by wireless communication devices102 and/or 104.

In some demonstrative embodiments, wireless communication devices 102and 104 may include, or may be associated with, one or more antennas 106and 108, respectively. Antennas 106 and/or 108 may include any type ofantennas suitable for transmitting and/or receiving wirelesscommunication signals, blocks, frames, transmission streams, packets,messages and/or data, e.g., over channel 110. For example, antennas 106and/or 108 may include any suitable configuration, structure and/orarrangement of one or more antenna elements, components, units,assemblies and/or arrays. Antennas 106 and/or 108 may include an antennacovered by a quasi-omni antenna pattern. For example, antennas 106and/or 108 may include at least one of a phased array antenna, a singleelement antenna, a set of switched beam antennas, and the like. In someembodiments, antennas 106 and/or 108 may implement transmit and receivefunctionalities using separate transmit and receive antenna elements. Insome embodiments, antennas 106 and/or 108 may implement transmit andreceive functionalities using common and/or integrated transmit/receiveelements.

In some demonstrative embodiments, device 102 may include a Time ofArrival (ToA) calculator to calculate a ToA 128 of a wirelesscommunication signal 114 received from device 104, e.g., as described indetail below. For example, wireless communication signal may include anOFDM signal or any other signal.

In some demonstrative embodiments, device 102 may utilize ToA 128 tocalculate, for example, a range, a distance, a location, and the like.For example, device 102 may calculate a location of device 102 and/ordistance between devices 102 and 104 base on the calculated ToA, e.g.,as described in detail below.

In some demonstrative embodiments, device 102 may include a locationcalculator 199 to calculate, for example, a range, a distance, and/orlocation of device 102 based on ToA 128, e.g., as described below.

In some demonstrative embodiments, a calculated ToA of the receivedsignal 114 may have a relatively low level of accuracy, for example, ifthe ToA is determined, e.g., in an indoor environment, by measuring atime of arrival of a first sample of an OFDM symbol of signal 114, e.g.,due to multipath interference. For example, using this measurement ofthe ToA may result in a relatively large positioning error, e.g., ofabout 50 meters or more. Accordingly, this measurement of the ToA maynot be accurate, for example, for indoor positioning and/or navigation.

In some demonstrative embodiments, ToA calculator 112 may be capable ofutilizing a ToA calculation, e.g., as described in detail below, whichmay result, for example, in ToA 128 having a relatively high degree ofaccuracy. For example, ToA 128 may have an error of less than 10nanoseconds (ns), for example, an error of no more than 5 ns, forexample, an error of 1 ns or less, e.g., an error of about 0.1 ns.

In some demonstrative embodiments, ToA calculator 112 may be configuredto determine ToA 128 of wireless communication signal 114 received overchannel 110 based on a detected symbol boundary of a symbol of signal114 and a channel estimation 116 of wireless communication channel 110,e.g., as described in detail below.

In some demonstrative embodiments, device 102 may include a channelestimator 117 to generate channel estimation 116, for example, accordingto a channel estimation scheme, e.g., utilizing channel stateinformation (CSI), and the like. Channel estimator 117 may beimplemented as part of ToA calculator 112, or as a separate element ofdevice 102.

In some demonstrative embodiments, ToA calculator 112 may determine ToA128 of wireless communication signal 114 based on a detected symbolboundary of an OFDM symbol of signal 114 and channel estimation 116 ofwireless communication channel 110, e.g., as described in detail below.

In some demonstrative embodiments, ToA calculator 112 may include a pathdelay estimator 120 to determine a path delay 124 corresponding towireless communication channel 110, for example, based on channelestimation 116.

In some demonstrative embodiments, ToA calculator 112 may include asymbol boundary detector 118 to detect a symbol boundary 122 of asymbol, e.g., a first symbol or any other particular symbol, of receivedsignal 114, e.g., as described in detail below.

In some demonstrative embodiments, ToA calculator 112 may include acalculator 126 to determine ToA 128 based on detected symbol boundary122 and path delay 124, e.g., as described in detail below.

In some demonstrative embodiments, path delay 124 may include a pathdelay corresponding to a particular path of channel 110.

In some demonstrative embodiments, path delay 124 may include a pathdelay of a Line of Sight (Los) path of channel 110, e.g., as describedbelow. In other embodiments, path delay 124 may include a path delay ofany other particular path of channel 110.

In some demonstrative embodiments, it may be difficult to identify,detect and/or extract the path delay of the particular path. Forexample, it may be difficult to identify, detect and/or extract the LoSpath delay, for example, if a LoS path is not the strongest path ofreceived signal 114, or if there are one or more other paths relativelyclose to the LoS path.

In some demonstrative embodiments, ToA calculator 112 may utilize aduality between a time domain and frequency domain, for example, toextract a particular path delay component from channel estimation 116.For example, a path delay component in the time domain may berepresented by a complex exponential in the frequency domain.Accordingly, ToA calculator 112 may extract the particular path delaycomponent from channel estimation 116 by extracting signal complexexponentials from channel estimation 116, and identifying a particularcomponent corresponding to the particular path delay, for example,identifying a component with a lowest frequency corresponding to a pathhaving a lowest path delay, e.g., as described below.

In some demonstrative embodiments, ToA calculator 112 may determine thepath delay 124 corresponding to wireless communication channel 110 byidentifying a discrete phase-vector (phasor) component of channelestimation 116 in the frequency domain; and determining the path delay124 according to a timing of the discrete phasor component.

The term “phasor” as used herein relates to a representation of timedelay in the frequency domain. The phasor frequency in the frequencydomain relates directly to the path delay and the amplitude relates tothe path component strength or power.

In some demonstrative embodiments, path delay estimator 120 may map apath delay in a time domain of signal 114 into a phasor including acomplex exponent in a frequency domain. The phasor frequency of thephasor in the frequency domain may be related to a value of the pathdelay. For example, a low phasor frequency may correspond to a shortpath delay.

In some demonstrative embodiments, path delay estimator 120 maydetermine path delay 124 by applying a super-resolutionfrequency-estimation algorithm to convert channel estimation 116 from afrequency domain into a time domain, e.g., with a finer resolutionlevel, e.g., as described in detail below.

In some demonstrative embodiments, the super-resolutionfrequency-estimation algorithm may include, for example, performing anEigen decomposition on a covariance matrix corresponding to channelestimation 116.

For example, path delay estimator may apply aMultiple-Signal-Classification (MUSIC) algorithm 173 to convert channelestimation 116 from the frequency domain to the time domain. In otherembodiments, the super-resolution frequency-estimation algorithm mayinclude any other algorithm and/or method.

In some demonstrative embodiments, MUSIC algorithm 173 may be used forextracting the LoS component timing, for example, in a sub sampleresolution, e.g., as described below with reference to FIG. 3.

In some demonstrative embodiments, MUSIC algorithm 173 may estimate afrequency content of channel estimation 116, for example, by performingan eigen decomposition on a covariance matrix corresponding to channelestimation 116. For example, MUSIC algorithm 173 may assume that asignal, denoted x(n), representing channel estimation 116 includes anumber, denoted p, of complex exponentials in the presence of Gaussianwhite noise. For example, given an M×M autocorrelation matrix, denotedRx, if the eigenvalues are sorted in decreasing order, the eigenvectorscorresponding to the p largest eigenvalues span the signal subspace ofthe signal x(n).

In some demonstrative embodiment, a MUSIC spectrum, denoted P_(MU),corresponding to channel estimation 116 may be determined by applyingMUSIC algorithm 173 to channel estimation 116. For example, the MUSICspectrum P_(MU) may be determined, e.g., as follows:

$\begin{matrix}{{{{\hat{P}}_{MU}\left( {\mathbb{e}}^{j\;\omega} \right)} = \frac{1}{\sum\limits_{i = {p + 1}}^{M}{{{\mathbb{e}}^{H}v_{i}}}^{2}}},} & (1)\end{matrix}$wherein v_(i) denotes an i-th noise eigenvector, and wherein:e=[1e ^(jω) e ^(j2ω) . . . e ^(j(M-1)ω)]^(T).  (2)

In some demonstrative embodiments, path delay estimator 120 may identifya lowest frequency phasor corresponding to channel estimation 116 in thetime domain, e.g., as described below. In other embodiments, path delayestimator 120 may identify another frequency phasor, e.g., asecond-lowest frequency phasor component, corresponding to channelestimation 116 in the time domain.

In some demonstrative embodiments, path delay estimator 120 may generatepath delay 124 including a time delay, denoted Δt, of the pathcorresponding to the identified phasor. For example, path delayestimator 120 may generate path delay 124 including the time delay Δt ofa path (“the lowest-delay path”) corresponding to the lowest frequencyphasor.

In some demonstrative embodiments, the lowest-delay path may correspondto the LoS path within the wireless communication channel 110. Forexample, path delay estimator 120 may apply the super-resolutionfrequency-estimation algorithm, e.g., MUSIC algorithm 173, to channelestimation 116 in the frequency domain. Path delay estimator 120 mayanalyze a resulting spectrum, e.g., a MUSIC spectrum, to detect andselect a peak corresponding to the LoS Path.

Reference is made to FIG. 3, which schematically illustrates a graph 300depicting a channel estimation sampled at a first sampling rate of 160Mega Hertz (MHz) in the frequency domain, a graph 302 depicting the samechannel estimation sampled at a second sampling rate of 40 MHz in thefrequency domain, a graph 304 depicting a channel impulse response ofthe same channel estimation sampled at the first sampling rate of 160MHz in the time domain, a graph 306 depicting the channel impulseresponse of the same channel estimation sampled at the second samplingrate of 40 MHz in the time domain, a graph 308 depicting a MUSICspectrum corresponding to the same channel estimation sampled at thefirst sampling rate of 160 MHz, and a graph 310 depicting the MUSICspectrum corresponding to the same channel estimation sampled at thesecond sampling rate of 40 MHz. For example, the MUSIC spectrums ofgraph 308 and 310 may be generated by applying MUSIC algorithm 173(FIG. 1) to channel estimation 116 (FIG. 1).

A shown in FIG. 3, it may be difficult to detect and/or identify one ormore paths from the channel estimation of in the frequency domain and/orfrom the channel impulse response of the same channel estimation, forexample, if the channel estimation is sampled at a relatively low rateand/or if the wireless communication channel has a relatively narrowbandwidth. For example, it may be difficult to detect and/or identifyone or more paths based on graphs 302 and 306.

As also shown in FIG. 3, one or more paths may be detected and/orestimated from the MUSIC spectrum of graphs 308 and 310, e.g., even ifthe channel estimation is sampled at a relatively low rate and/or if thewireless communication channel has a relatively narrow bandwidth. Forexample, one or more paths may be detected and/or estimated based ongraph 310

Referring back to FIG. 1, in some demonstrative embodiments, path delayestimator 120 may detect the particular path delay based on the MUSICspectrum, e.g., based on the MUSIC spectrums of graphs 308 and/or 310(FIG. 1). For example, path delay estimator 120 may determine aderivative of the MUSIC spectrum to determine positions of one or morelocal maximums of the MUSIC spectrum, and detect the particular pathdelay by detecting a corresponding local maximum. For example, pathdelay estimator 120 may detect the lowest delay path be detecting afirst local maximum in the derivative of the MUSIC spectrum, e.g., bydetecting a farthest left peak of the MUSIC spectrums of graphs 308and/or 306 (FIG. 1).

In some demonstrative embodiments, path delay estimator 120 may utilizeany noise handling, false-peak removal algorithm, filtering algorithm,and the like, to handle and/or remove any noise affecting the MUSICspectrum.

Although some demonstrative embodiments are described above withreference to determining the path delay based on an identified phasor,in other embodiments the path delay may be determined by analyzingchannel estimation 116 in time domain. For a super-resolution algorithmmay be applied to the channel estimation 116 in time domain, forexample, a blind signal separation (BSS) algorithm, e.g., an Independentcomponent analysis (ICA), and the like.

In some demonstrative embodiments, symbol boundary detector 118 maygenerate symbol boundary 122 including a symbol boundary time, denotedt_(symbStart), of a sample, e.g., the first sample, of a symbol, e.g.,an OFDM symbol, of signal 114. In some embodiments, symbol boundary 122may relate to a first OFDM symbol of signal 114, e.g., as describedherein. In other embodiments, symbol boundary 122 may relate to anyother particular symbol of signal 114.

In some demonstrative embodiments, calculator 126 may determine ToA 128based on a combination of symbol boundary 122 and path delay 124.

In some demonstrative embodiments, calculator 126 may determine ToA 128while considering a predefined delay, denoted, t_(HW-delay), associatedwith one or more components of device 102. For example, the delayt_(HW-delay) may include a delay, e.g., a fixed delay, resulting fromone or more hardware and/or software components of device 102.

In one example, the delay t_(HW-delay) may include a delay caused byantenna 106, and/or analog and/or digital circuitry of device 102, whichmay be used to process signal 114. The delay t_(HW-delay) may bedetermined, for example, based on measurements.

In some demonstrative embodiments, calculator 126 may determine ToA 128,denoted t_(ToA), based on a combination of the time t_(symbStart), thetime delay Δt and the delay t_(HW-delay), e.g., as follows:t _(ToA) =t _(symbStart) +Δt−t _(HW-delay)  (3)

In some demonstrative embodiments, the calculation of the ToA, e.g.,according to Equation 3, may yield ToA 128 having a relatively highdegree of accuracy. For example, ToA 128 may have an error of 10nanoseconds (ns) or less. For example, ToA calculator 112 may calculateToA 128 at a resolution of no more than 5 ns, for example, 1 ns or less,e.g., about 0.1 ns.

FIG. 2 schematically illustrates the time components utilized fordetermining the ToA t_(ToA) according to Equation 3, in accordance withsome demonstrative embodiments.

In some demonstrative embodiments, location calculator 199 may determinea location of device 102 based on ToA 128, e.g., as described below.

In some demonstrative embodiments, location calculator 199 may determinea time-of-flight (ToF) between device 102 and a transmitter of signal114, e.g., device 104, based on ToA 128, e.g., as described in detailbelow. The ToF between device 102 and device 104 may include a timerequired for a signal, e.g., signal 114, to travel from device 104 todevice 102.

Reference is made to FIG. 4, which schematically illustrates a sequencediagram 400, which demonstrates operations and interactions between afirst device 402, e.g., device 102 (FIG. 1), and a second device, e.g.,device 104 (FIG. 1), along a timeline 409, in accordance with somedemonstrative embodiments. In one example, device 402 may include amobile station and device 404 may include an AP.

In some demonstrative embodiments, one or more of the operations ofsequence 400 may be performed by devices 402 and/or 404 in order todetermine at least one location-related parameter, e.g., a relativelocation (“range”) between devices 402 and 404.

In some demonstrative embodiments, device 402 may transmit a message410, denoted M1, to device 404, at a time, denoted t1. The time t1 maybe a Time of Departure (ToD), denoted ToD(M1), of the message M1.

In some demonstrative embodiments, device 404 may receive message 410and determine a time, denoted t2, e.g., by determining a ToA, denotedToA(M1), of message 410. For example, device 404 may determine the timet2 according to Equation 3, e.g., as described above.

In some demonstrative embodiments, device 404 may transmit a message412, denoted M1-ACK, to device 402, at a time, denoted t3. Message 412may include, for example, an acknowledgement message transmitted inresponse to message 410. The time t3 may be a ToD, denoted ToD(M1-ACK),of the message M1-ACK.

In some demonstrative embodiments, device 402 may receive message 412and determine a time, denoted t4, e.g., by determining a ToA, denotedToA(M1-ACK), of message 412. For example, device 402 may determine thetime t4 according to Equation 3, e.g., as described above.

In some demonstrative embodiments, device 404 may transmit a message414, denoted M2, to device 402. Message 414 may include, for example,information corresponding to the time t2 and/or the time t3. Forexample, message 414 may include a timestamp, e.g., a ToA timestamp,including the time t2, and a timestamp, e.g., a ToD timestamp, includingthe time t3.

In some demonstrative embodiments, device 402 may receive message 414.Device 402 may determine a ToF between devices 402 and 404, for example,based on message 414.

For example, device 402 may determine the ToF based on an average, orany other function, applied to the time values t1, t2, t3 and t4. Forexample, device 402 may determine the ToF, e.g., as follows:ToF=[(t4−t1)−(t3−t2)]/2  (4)

In some demonstrative embodiments, device 402 may transmit a message416, denoted M2-ACK, to device 404. Message 416 may include, forexample, an acknowledgement message transmitted in response to message414.

In some demonstrative embodiments, device 402 may determine the rangebetween devices 402 and 404 based on the calculated ToF.

For example, device 402 may determine the range, denoted r_(k), e.g., asfollows:r _(k)=ToF*C  (5)wherein C denotes the radio wave propagation speed.

In some demonstrative embodiments, device 402 may determine a locationof device 402, e.g., an absolute location of device 402, based on theestimated range r_(k).

For example, device 402 may include location calculator 199 (FIG. 1) todetermine two or more ToF values, e.g., according to Equation 5, withrespect to two or more respective devices 404. Location calculator 199(FIG. 1) may determine the location of device 402 based on the two ormore ToF values, e.g., by trilateration.

As discussed above, the ToA my have a relatively high degree ofaccuracy. For example, ToA 128 (FIG. 1) may have an error of 10nanoseconds (ns) or less. Accordingly, the ToA timestamp f message 414may have a resolution of no more than 5 ns, for example, 1 ns or less,e.g., about 0.1 ns. As a result, device 402 may be capable ofdetermining the range r_(k) with a relatively high degree of accuracy,for example, an accuracy of 1 meter (m) or less, e.g., an accuracy of0.3 m or less if a resolution of 1 ns is used, or even an accuracy of0.03 m or less if a resolution of 0.1 ns is used.

Reference is made to FIG. 5, which schematically illustrates a method ofdetermining a ToA of a wireless communication signal, in accordance withsome demonstrative embodiments. In some embodiments, one or more of theoperations of the method of FIG. 5 may be performed by any suitablewireless communication system, e.g., system 100 (FIG. 1), wirelesscommunication device, e.g., device 102 and/or device 104 (FIG. 1),and/or ToA calculator, e.g., ToA calculator 112 (FIG. 1).

As indicated at block 502, the method may include receiving a signalover a wireless communication channel. For example, device 102 (FIG. 1)may receive signal 114 (FIG. 1), e.g., as described above.

As indicated at block 504, the method may include detecting a symbolboundary of a symbol of the received signal. For example, symbolboundary detector 118 (FIG. 1) may detect symbol boundary 122 (FIG. 1),e.g., as described above.

As indicated at block 506, the method may include determining the ToA ofthe received signal based on the symbol boundary and a channelestimation of the wireless communication channel. For example, ToAcalculator 112 (FIG. 1) may determine ToA 128 (FIG. 1), e.g., asdescribed above.

As indicated at block 508, determining the ToA of the received signalmay include determining a path delay corresponding to the wirelesscommunication channel based on the channel estimation, and determiningthe ToA of the received signal based on the symbol boundary and the pathdelay. For example, path delay estimator 120 (FIG. 1) may determine pathdelay 124 (FIG. 1), and calculator 126 (FIG. 1) may determine ToA 128(FIG. 1) based on symbol boundary 122 (FIG. 1) and path delay 124 (FIG.1), e.g., as described above.

As indicated at block 510, determining the path delay may includeidentifying a discrete phase vector (phasor) component of the channelestimation in a frequency domain.

As indicated at block 512, identifying the discrete phasor component mayinclude identifying a lowest phasor component of the channel estimationin the frequency domain. For example, the path delay may include a LoSpath delay corresponding to the wireless communication channel, e.g., asdescribed above.

In some demonstrative embodiments, determining the path delay mayinclude performing an Eigen decomposition on a covariance matrixcorresponding to the channel estimation, e.g., as descried above.

In some demonstrative embodiments, determining the path delay mayinclude applying a super-resolution frequency-estimation algorithm,e.g., a MUSIC algorithm, to convert the channel estimation from afrequency domain into a time domain. For example, path delay estimator120 (FIG. 1) may apply MUSIC algorithm 173 (FIG. 1), e.g., as describedabove.

As indicated at block 514, determining the path delay may includedetermining the path delay according to a timing of the discrete phasorcomponent. path delay estimator 120 (FIG. 1) may determine path delay124 (FIG. 1) based on the timing of the LoS component, e.g., asdescribed above.

As indicated at block 516, the method may include determining a ToFbetween a receiver of the received signal and a transmitter of thereceived signal based on the ToA. For example, location calculator 199(FIG. 1) may determine the ToF based on ToA 128 (FIG. 1), e.g., asdescribed above.

As indicated at block 516, the method may include determining a locationof the receiver of the signal based on the ToA. For example, locationcalculator 199 (FIG. 1) may determine a location of device 102 (FIG. 1)based on the ToF, e.g., as described above.

Reference is made to FIG. 6, which schematically illustrates an articleof manufacture 600, in accordance with some demonstrative embodiments.Article 600 may include a non-transitory machine-readable storage medium602 to store logic 604, which may be used, for example, to perform atleast part of the functionality of ToA calculator 112 (FIG. 1), locationcalculator 199 (FIG. 1) and/or to perform one or more operations of themethod of FIG. 5. The phrase “non-transitory machine-readable medium” isdirected to include all computer-readable media, with the sole exceptionbeing a transitory propagating signal.

In some demonstrative embodiments, article 600 and/or machine-readablestorage medium 602 may include one or more types of computer-readablestorage media capable of storing data, including volatile memory,non-volatile memory, removable or non-removable memory, erasable ornon-erasable memory, writeable or re-writeable memory, and the like. Forexample, machine-readable storage medium 602 may include, RAM, DRAM,Double-Data-Rate DRAM (DDR-DRAM), SDRAM, static RAM (SRAM), ROM,programmable ROM (PROM), erasable programmable ROM (EPROM), electricallyerasable programmable ROM (EEPROM), Compact Disk ROM (CD-ROM), CompactDisk Recordable (CD-R), Compact Disk Rewriteable (CD-RW), flash memory(e.g., NOR or NAND flash memory), content addressable memory (CAM),polymer memory, phase-change memory, ferroelectric memory,silicon-oxide-nitride-oxide-silicon (SONOS) memory, a disk, a floppydisk, a hard drive, an optical disk, a magnetic disk, a card, a magneticcard, an optical card, a tape, a cassette, and the like. Thecomputer-readable storage media may include any suitable media involvedwith downloading or transferring a computer program from a remotecomputer to a requesting computer carried by data signals embodied in acarrier wave or other propagation medium through a communication link,e.g., a modem, radio or network connection.

In some demonstrative embodiments, logic 604 may include instructions,data, and/or code, which, if executed by a machine, may cause themachine to perform a method, process and/or operations as describedherein. The machine may include, for example, any suitable processingplatform, computing platform, computing device, processing device,computing system, processing system, computer, processor, or the like,and may be implemented using any suitable combination of hardware,software, firmware, and the like.

In some demonstrative embodiments, logic 604 may include, or may beimplemented as, software, a software module, an application, a program,a subroutine, instructions, an instruction set, computing code, words,values, symbols, and the like. The instructions may include any suitabletype of code, such as source code, compiled code, interpreted code,executable code, static code, dynamic code, and the like. Theinstructions may be implemented according to a predefined computerlanguage, manner or syntax, for instructing a processor to perform acertain function. The instructions may be implemented using any suitablehigh-level, low-level, object-oriented, visual, compiled and/orinterpreted programming language, such as C, C++, Java, BASIC, Matlab,Pascal, Visual BASIC, assembly language, machine code, and the like.

Functions, operations, components and/or features described herein withreference to one or more embodiments, may be combined with, or may beutilized in combination with, one or more other functions, operations,components and/or features described herein with reference to one ormore other embodiments, or vice versa.

While certain features of the invention have been illustrated anddescribed herein, many modifications, substitutions, changes, andequivalents may occur to those skilled in the art. It is, therefore, tobe understood that the appended claims are intended to cover all suchmodifications and changes as fall within the true spirit of theinvention.

What is claimed is:
 1. A method comprising: receiving a signal over awireless communication channel; detecting a symbol boundary of a symbolof said signal; and determining a time of arrival (ToA) of said signalbased on said symbol boundary and a channel estimation of said wirelesscommunication channel, wherein determining said ToA comprises:identifying a discrete phase vector (phasor) component of said channelestimation in a frequency domain; determining a path delay correspondingto said wireless communication channel according to a timing of saiddiscrete phasor component; and determining said ToA of said signal basedon said symbol boundary and said path delay.
 2. The method of claim 1comprising: determining a time-of-flight (ToF) between a receiver ofsaid signal and a transmitter of said signal based on the ToA of saidsignal.
 3. The method of claim 1, wherein identifying said discretephasor component comprises identifying a lowest phasor component of saidchannel estimation in said frequency domain.
 4. The method of claim 1,wherein said path delay comprises a line-of-sight (LoS) path delaycorresponding to a LoS path within said wireless communication channel.5. A method comprising: receiving a signal over a wireless communicationchannel; detecting a symbol boundary of a symbol of said signal;determining a time of arrival (ToA) of said signal based on said symbolboundary and a channel estimation of said wireless communicationchannel, wherein determining said ToA comprises: identifying a lowestphasor component of said channel estimation in a frequency domain;determining a line-of-sight (LoS) path delay corresponding to a LoS pathwithin said wireless communication channel according to a timing of saidlowest phasor component; and determining said ToA of said signal basedon said symbol boundary and said LoS path delay.
 6. The method of claim1, wherein determining said path delay comprises performing an eigendecomposition on a covariance matrix corresponding to said channelestimation.
 7. The method of claim 1, wherein determining said pathdelay comprises applying a super-resolution frequency-estimationalgorithm to convert said channel estimation from a frequency domaininto a time domain.
 8. The method of claim 7, wherein saidsuper-resolution frequency-estimation algorithm comprises aMultiple-Signal-Classification (MUSIC) algorithm.
 9. The method of claim5 comprising determining a time-of-flight (ToF) between a receiver ofsaid signal and a transmitter of said signal based on the ToA of saidsignal.
 10. The method of claim 1 comprising determining a location of areceiver of said signal based on the ToA of said signal.
 11. The methodof claim 1, wherein detecting said symbol boundary comprises detecting aToA of said symbol.
 12. The method of claim 1, wherein said signalcomprises an Orthogonal-Frequency-Division-Multiplexing (OFDM) signal,and said symbol comprises an OFDM symbol.
 13. A wireless communicationdevice comprising: a radio configured to communicate over a wirelesscommunication channel; and a time of arrival (ToA) calculator componentconfigured to calculate a ToA of a signal received over said wirelesscommunication channel based on a detected symbol boundary of a symbol ofsaid signal and a channel estimation of said wireless communicationchannel, said ToA calculator component is configured to identity adiscrete phase vector (phasor) component of said channel estimation in afrequency domain, to determine a path delay corresponding to saidwireless communication channel according to a timing of said discretephasor component, and to determine said ToA of said signal based on saidsymbol boundary and said path delay.
 14. The wireless communicationdevice of claim 13, wherein the ToA calculator component is configuredto determine said path delay by performing an eigen decomposition on acovariance matrix corresponding to said channel estimation.
 15. Thewireless communication device of claim 13, wherein said ToA calculatorcomponent is configured to detect said symbol boundary by detecting aToA of said symbol.
 16. The wireless communication device of claim 13,wherein said path delay comprises a line-of-sight (LoS) path delaycorresponding to a LoS path within said wireless communication channel.17. The wireless communication device of claim 13, wherein said pathdelay estimator component is configured to determine said path delay byapplying a super-resolution frequency-estimation algorithm to convertsaid channel estimation from a frequency domain into a time domain. 18.The wireless communication device of claim 13 comprising a locationcalculator component to determine one or more location-related valuescorresponding to a location of said wireless communication device basedon the ToA of said signal.
 19. A wireless communication systemcomprising: a wireless communication device configured to receive afirst message from another wireless communication device over a wirelesscommunication channel, to calculate a time of arrival (ToA) of saidfirst message based on a detected symbol boundary of a symbol of saidfirst message and a channel estimation of said wireless communicationchannel, and to transmit to the another wireless communication device asecond message including a value corresponding to said ToA, saidwireless communication device is configured to identify a discrete phasevector (phasor) component of said channel estimation in a frequencydomain, to determine a path delay corresponding to said wirelesscommunication channel according to a timing of said discrete phasorcomponent, and to determine the ToA of said first message based on saidsymbol boundary and said path delay.
 20. The wireless communicationsystem of claim 19, wherein said ToA has an error of no more than 1nanosecond.
 21. The wireless communication system of claim 19, whereinthe wireless communication device is configured to determine said pathdelay by applying a super-resolution frequency-estimation algorithm toconvert said channel estimation from a frequency domain into a timedomain.
 22. The wireless communication system of claim 19 wherein thewireless communication device is configured to determine atime-of-flight (ToF) between a receiver of said signal and a transmitterof said signal based on the ToA of said signal.
 23. A product includinga non-transitory storage medium having stored thereon instructions that,when executed by a machine, result in: calculating a time of arrival(ToA) of a wireless communication signal received over a wirelesscommunication channel based on a channel estimation of said wirelesscommunication channel and a detected symbol boundary of a symbol of saidwireless communication signal, calculating the ToA of said wirelesscommunication signal comprises: identifying a discrete phase vector(phasor) component of said channel estimation in a frequency domain;determining a path delay corresponding to said wireless communicationchannel according to a timing of said discrete phasor component; anddetermining the ToA of said wireless communication signal based on saidsymbol boundary and said path delay.
 24. The product of claim 23,wherein determining said path delay comprises performing an eigendecomposition on a covariance matrix corresponding to said channelestimation.
 25. The product of claim 23, wherein detecting said symbolboundary comprises detecting a ToA of said symbol.